Holographic near-eye display system based on double-convergence light Gerchberg-Saxton algorithm

Author(s):

Peng Sun and Shengqian Chang and Siqi Liu and Xiao Tao and Chang Wang and Zhenrong Zheng

Abstract:

“In this paper, a method is proposed to implement noises reduced three-dimensional (3D) holographic near-eye display by phase-only computer-generated hologram (CGH). The CGH is calculated from a double-convergence light Gerchberg-Saxton (GS) algorithm, in which the phases of two virtual convergence lights are introduced into GS algorithm simultaneously. The first phase of convergence light is a replacement of random phase as the iterative initial value and the second phase of convergence light will modulate the phase distribution calculated by GS algorithm. Both simulations and experiments are carried out to verify the feasibility of the proposed method. The results indicate that this method can effectively reduce the noises in the reconstruction. Field of view (FOV) of the reconstructed image reaches 40 degrees and experimental light path in the 4-f system is shortened. As for 3D experiments, the results demonstrate that the proposed algorithm can present 3D images with 180cm zooming range and continuous depth cues. This method may provide a promising solution in future 3D augmented reality (AR) realization.”

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Publication: Optics Express

Issue/Year/DOI: Optics Express, Vol. 26, Issue 8, pp. 10140- 10151 (2018)
DOI: 10.1364/OE.26.010140

Superresolution far-field imaging of complex objects using reduced superoscillating ripples

Author(s):

Xiao Han Dong and Alex M. H. Wong and Minseok Kim and George V. Eleftheriades

Abstract:

“Superoscillation is a phenomenon where a wave oscillates locally faster than its highest Fourier component. While previous reports have shown attractive possibilities for a superoscillation-based far-field superresolution imaging device, it has also been recognized that a high-energy “sideband” region coexists with the superresolution features. This sideband causes strong restrictions and necessitates trade-offs in achievable resolution, viewing area, and sensitivity of the imaging device. In this work, we introduce a new class of superoscillation waveform—which consists of a diffraction-limited hotspot surrounded by low-energy superoscillating sidelobe ripples. This waveform alleviates the aforementioned trade-off and enables superresolution imaging for complex objects over a larger viewing area while maintaining a practical level of sensitivity. Using this waveform as the point spread function of an imaging system, we demonstrate the successful superresolution of Latin letters without performing scanning and/or post-processing operations.”

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Publication: Optica

Issue/Year/DOI: Optica, Vol. 4, Issue 9, pp. 1126-1133 (2017)
DOI: 10.1364/OPTICA.4.001126

Dynamic three-dimensional multifocal spots in high numerical-aperture objectives

Author(s):

Linwei Zhu and Rui Yang and Dawei Zhang and Junjie Yu and Jiannong Chen

Abstract:

“Multifocal spots in high numerical-aperture (NA) objectives has emerged as a rapid, parallel, and multi-location method in a multitude of applications. However, the typical method used for forming three-dimensional (3D) multifocal spots based on iterative algorithms limits the potential applications. We demonstrate a non-iterative method using annular subzone phases (ASPs) that are composed of many annular subareas in which phase-only distributions with different 3D displacements are filled. The dynamic 3D multifocal spots with controllable position of each focal spot in the focal volume of the objective are created using the ASPs. The experimental results of such dynamic tunable 3D multifocal spots offer the possibility of versatile process in laser 3D fabrication, optical trapping, and fast focusing scanned microscopic imaging.”

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Publication: Optics Express

Issue/Year/DOI: Optics Express, Vol. 25, Issue 20, pp. 24756- 24766 (2018)
DOI: 10.1364/OE.25.024756

Robust laser beam engineering using polarization and angular momentum diversity

Author(s):

Priyanka Lochab and P. Senthilkumaran and Kedar Khare

Abstract:

“We describe a laser beam engineered to carry l = 0 and l = 1 orbital angular momentum (OAM) states in orthogonal polarizations. It is observed that on collinear transmission through a random phase screen, the far field diffraction intensity patterns for the individual polarization states are complementary with significant negative correlation. As a result the combined intensity profile for the beam remains robust against time varying phase fluctuations. In our simulation and experiment the SNR for the central lobe of the combined far-field diffraction pattern defined as mean divided by the standard deviation of intensity values shows significant improvement over that for individual polarizations. The concept of polarization and OAM diversity as demonstrated here can be considered valuable for robust laser beam engineering without the requirement of any active real-time correction methods.”

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Publication: Optics Express

Issue/Year/DOI: Optics Express, Vol. 25 , Issue 15 , pp. 17524-17524 (2018)
DOI: 10.1364/OE.25.017524

Computational super-resolution phase retrieval from multiple phase-coded diffraction patterns: simulation study and experiments

Author(s):

Vladimir Katkovnik and Igor Shevkunov and Nikolay V. Petrov and Karen Egiazarian

Abstract:

“In this paper, we consider computational super-resolution inverse diffraction phase retrieval. The optical setup is lensless, with a spatial light modulator for aperture phase coding. The paper is focused on experimental tests of the super-resolution sparse phase amplitude retrieval algorithm. We start from simulations and proceed to physical experiments. Both simulation tests and experiments demonstrate good-quality imaging for super-resolution with a factor of 4 and a serious advantage over diffraction-limited resolution as defined by Abbe’s criterion.”

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Publication: Optica

Issue/Year/DOI: Optica , Vol. 4, Issue 7, (2017)
DOI: 10.1364/OPTICA.4.000786

Nature does not rely on long-lived electronic quantum coherence for photosynthetic energy transfer.

Author(s):

Duan, Hong-Guang and Prokhorenko, Valentyn I. and Cogdell, Richard J. and Ashraf, Khuram and Stevens, Amy L. and Thorwart, Michael and Miller, R. J. Dwayne

Abstract:

“We have revisited the 2D spectroscopy of the excitation energy transfer in the Fenna-Matthews-Olson (FMO) protein. Based on 2D spectroscopic signatures, the energy transfer dynamics in the FMO protein has been argued to be supported by long-lived electronic quantum coherence on timescales up to 1.5 ps. In contrast, our analysis, based on experimental data and confirmed by theoretical calculations, shows that the electronic decoherence occurs within 60 fs, in agreement with typical dephasing times in systems under these conditions. Given the relatively well-defined structure of the FMO protein, and comparative couplings between chlorophylls to other photosynthetic systems, the observed extremely fast decoherence should be viewed as general, bringing to question any significant quantum coherent transport contributions to photosynthesis.”

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Publication: Proceedings of the National Academy of Sciences of the United States of America

Issue/Year/DOI:
DOI: 10.1073/pnas.1702261114